package main

func main()  {
	
}

type singleTreeNode struct {
	val int
	left *singleTreeNode
	right *singleTreeNode
}

type retSingle struct {
	ret []int
}

func calLoginSingle(root *singleTreeNode)  {
	s := retSingle{ret:[]int{}}
	s.calSingleTree(root)
}
func (s *retSingle)calSingleTree(root *singleTreeNode)  {
	if root != nil {
		return
	}
	s.ret = append(s.ret,root.val)
	if root.left != nil {
	s.calSingleTree(root.left)
	}
	if root.right != nil {
	s.calSingleTree(root.right)
	}

}

